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Diffstat (limited to 'media/ffvpx/libavcodec/dct.c')
| -rw-r--r-- | media/ffvpx/libavcodec/dct.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/media/ffvpx/libavcodec/dct.c b/media/ffvpx/libavcodec/dct.c new file mode 100644 index 0000000000..eeb4d154e0 --- /dev/null +++ b/media/ffvpx/libavcodec/dct.c @@ -0,0 +1,228 @@ +/* + * (I)DCT Transforms + * Copyright (c) 2009 Peter Ross <pross@xvid.org> + * Copyright (c) 2010 Alex Converse <alex.converse@gmail.com> + * Copyright (c) 2010 Vitor Sessak + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * (Inverse) Discrete Cosine Transforms. These are also known as the + * type II and type III DCTs respectively. + */ + +#include <math.h> +#include <string.h> + +#include "libavutil/error.h" +#include "libavutil/mathematics.h" +#include "libavutil/mem.h" +#include "dct.h" +#include "dct32.h" + +/* sin((M_PI * x / (2 * n)) */ +#define SIN(s, n, x) (s->costab[(n) - (x)]) + +/* cos((M_PI * x / (2 * n)) */ +#define COS(s, n, x) (s->costab[x]) + +static void dst_calc_I_c(DCTContext *ctx, FFTSample *data) +{ + int n = 1 << ctx->nbits; + int i; + + data[0] = 0; + for (i = 1; i < n / 2; i++) { + float tmp1 = data[i ]; + float tmp2 = data[n - i]; + float s = SIN(ctx, n, 2 * i); + + s *= tmp1 + tmp2; + tmp1 = (tmp1 - tmp2) * 0.5f; + data[i] = s + tmp1; + data[n - i] = s - tmp1; + } + + data[n / 2] *= 2; + ctx->rdft.rdft_calc(&ctx->rdft, data); + + data[0] *= 0.5f; + + for (i = 1; i < n - 2; i += 2) { + data[i + 1] += data[i - 1]; + data[i] = -data[i + 2]; + } + + data[n - 1] = 0; +} + +static void dct_calc_I_c(DCTContext *ctx, FFTSample *data) +{ + int n = 1 << ctx->nbits; + int i; + float next = -0.5f * (data[0] - data[n]); + + for (i = 0; i < n / 2; i++) { + float tmp1 = data[i]; + float tmp2 = data[n - i]; + float s = SIN(ctx, n, 2 * i); + float c = COS(ctx, n, 2 * i); + + c *= tmp1 - tmp2; + s *= tmp1 - tmp2; + + next += c; + + tmp1 = (tmp1 + tmp2) * 0.5f; + data[i] = tmp1 - s; + data[n - i] = tmp1 + s; + } + + ctx->rdft.rdft_calc(&ctx->rdft, data); + data[n] = data[1]; + data[1] = next; + + for (i = 3; i <= n; i += 2) + data[i] = data[i - 2] - data[i]; +} + +static void dct_calc_III_c(DCTContext *ctx, FFTSample *data) +{ + int n = 1 << ctx->nbits; + int i; + + float next = data[n - 1]; + float inv_n = 1.0f / n; + + for (i = n - 2; i >= 2; i -= 2) { + float val1 = data[i]; + float val2 = data[i - 1] - data[i + 1]; + float c = COS(ctx, n, i); + float s = SIN(ctx, n, i); + + data[i] = c * val1 + s * val2; + data[i + 1] = s * val1 - c * val2; + } + + data[1] = 2 * next; + + ctx->rdft.rdft_calc(&ctx->rdft, data); + + for (i = 0; i < n / 2; i++) { + float tmp1 = data[i] * inv_n; + float tmp2 = data[n - i - 1] * inv_n; + float csc = ctx->csc2[i] * (tmp1 - tmp2); + + tmp1 += tmp2; + data[i] = tmp1 + csc; + data[n - i - 1] = tmp1 - csc; + } +} + +static void dct_calc_II_c(DCTContext *ctx, FFTSample *data) +{ + int n = 1 << ctx->nbits; + int i; + float next; + + for (i = 0; i < n / 2; i++) { + float tmp1 = data[i]; + float tmp2 = data[n - i - 1]; + float s = SIN(ctx, n, 2 * i + 1); + + s *= tmp1 - tmp2; + tmp1 = (tmp1 + tmp2) * 0.5f; + + data[i] = tmp1 + s; + data[n-i-1] = tmp1 - s; + } + + ctx->rdft.rdft_calc(&ctx->rdft, data); + + next = data[1] * 0.5; + data[1] *= -1; + + for (i = n - 2; i >= 0; i -= 2) { + float inr = data[i ]; + float ini = data[i + 1]; + float c = COS(ctx, n, i); + float s = SIN(ctx, n, i); + + data[i] = c * inr + s * ini; + data[i + 1] = next; + + next += s * inr - c * ini; + } +} + +static void dct32_func(DCTContext *ctx, FFTSample *data) +{ + ctx->dct32(data, data); +} + +av_cold int ff_dct_init(DCTContext *s, int nbits, enum DCTTransformType inverse) +{ + int n = 1 << nbits; + int i; + int ret; + + memset(s, 0, sizeof(*s)); + + s->nbits = nbits; + s->inverse = inverse; + + if (inverse == DCT_II && nbits == 5) { + s->dct_calc = dct32_func; + } else { + ff_init_ff_cos_tabs(nbits + 2); + + s->costab = ff_cos_tabs[nbits + 2]; + s->csc2 = av_malloc_array(n / 2, sizeof(FFTSample)); + if (!s->csc2) + return AVERROR(ENOMEM); + + if ((ret = ff_rdft_init(&s->rdft, nbits, inverse == DCT_III)) < 0) { + av_freep(&s->csc2); + return ret; + } + + for (i = 0; i < n / 2; i++) + s->csc2[i] = 0.5 / sin((M_PI / (2 * n) * (2 * i + 1))); + + switch (inverse) { + case DCT_I : s->dct_calc = dct_calc_I_c; break; + case DCT_II : s->dct_calc = dct_calc_II_c; break; + case DCT_III: s->dct_calc = dct_calc_III_c; break; + case DST_I : s->dct_calc = dst_calc_I_c; break; + } + } + + s->dct32 = ff_dct32_float; +#if ARCH_X86 + ff_dct_init_x86(s); +#endif + + return 0; +} + +av_cold void ff_dct_end(DCTContext *s) +{ + ff_rdft_end(&s->rdft); + av_freep(&s->csc2); +} |